http://www.freep.com/article/20090809/COL21/908090316

Q: Right now, travelers can still buy a Northwest ticket well into next year. What happens when the Northwest brand goes away, say, in February, and all the flights suddenly become Delta?

A: We are trying to make the process seamless for customers. Most flights will stay the same. You mostly likely will be able to use the same reservations.

What this says to me is one day the frequent-flyer programs will combine, and even all-new 012 reservations will go away (meaning only 006?), yet 012 will be around for 300+ more days, as the 012 reservation queue is cleared out.

The rules still appears to apply... for best customer service experience, buy the 006/012 ticket for the metal you fly, and watch out for mixed-metal flights. If possible, try to gauge when 006 will take over, and buy only 006 ticket for after that date. The fewer 012 tickets that remain, the fewer reps that will be able to handle ir-ops for 012, and the harder it will be for those impacted.

As soon as 012 new-sales go away, the thread-of-the-day will be "noone knows how to handle an 012 ticket!". I can see a day when they pull the hardware and data lines from the smallest out-stations, and all changes have to be done over the phone by the 006 agent.